1. Field of the Invention
The present invention relates to a sensing technique using a capacitance touch sensor as a user interface, and more particularly, to an apparatus, method, and medium for sensing the movement of fingers using a touch sensor capable of sensing at least one touch point in which a signal output by a multi-touch sensor is analyzed, the number of a user's fingers that touch the multi-touch sensor and the movement of the fingers are detected based on the results of the analysis, and a scroll operation performed by the user is determined based on the results of the detection.
2. Description of the Related Art
Press switches widely used in home appliances or liquid crystal monitors have been increasingly replaced by touch switches. Touch switches generally include an electrode which is installed beneath a front cover. Thus, touch switches sense variations in the capacitance between an electrode and a user who touches the electrode, and provide the results of the sensing to microprocessors or microcomputers as switch signals.
Touch switches are classified into touch switches that sense variations in the capacitance between an electrode installed in each of the touch switches and a finger of a person who touches the electrode and touch switches that sense inductance variations or impedance variations.
Touch sensors that sense capacitance variations react not only to a user's fingers but also to other parts of the user's body or other conductive materials, thereby causing touch user interface systems equipped with such touch sensors to malfunction. In order to address this problem, a variety of techniques of improving the reliability of touch sensors through sensor signal processing have been suggested, and examples of these techniques are as follows.
First, there is a technique of improving the reliability of touch sensors through sensor signal processing that involves recognizing whichever of a plurality of touch sensors has been least recently fired is recognized when the touch sensors are all fired. This technique, however, may cause malfunctions especially when a signal output by whichever of a plurality of touch sensors has been least recently fired is noise (for example, when a scroll operation is performed when a user accidentally touches a touch sensor).
Second, there is a technique of improving the reliability of touch sensors through sensor signal processing. This technique aims at improving the reliability of touch user interfaces through multi-touch sensing, thereby enabling a touch screen capable of sensing only one touch point to be able to sense more than one touch point through signal processing. In detail, in this technique, estimated X and Y coordinates are determined based on the intensities of signals input from the X- and Y-axes of a touch screen, and whichever of a plurality of pairs of X and Y coordinates that can be generated based on the estimated X and Y coordinates is most reliable is determined as a final pair of coordinates. According to this technique, it is possible to determine whether one or more touch points are currently detected based on signals received from a touch screen, determine the position of each detected touch point, and determine which of a plurality of touch points that have been detected is a valid touch point. However, since conventional touch sensors can only detect a single touch point at a time, the number of touch points that can be detected using this technique is limited to a maximum of 2. Therefore, when two or more touch sensor signals are generated due to unintentional touches by a user's hand or fingers, it is difficult to detect intentional touches by the user's hand or fingers using this technique. Thus, the performance of the detection of touch signals generated by intentional touches by a user's hand or fingers considerably decreases.